摘要：
Spin-controlled vortex generation is a manifestation of the spin-orbit interaction (SOI) of light, which has been extensively studied in Pancharatnam-Berry geometric phase elements in recent years. The SOI under the normal incidence of a light beam at a sharp interface, also shown by a spin-dependent vortex, has attracted little attention, except for a few exceptions. Here, we establish a Fresnel Jones matrix to fully describe the dynamics of beam reflection and refraction at sharp interfaces under normal incidence. It is pointed out that the vortex phase originates from the topological structure of the beam itself and is essentially a spin-redirection Berry phase. Although the geometric phase in Pancharatnam-Berry elements comes from the anisotropy of the external material, which shows a fundamental difference, they are the same in form. We then give a comparative study of the two kinds of SOI, and reveal the intrinsic connection and difference between them. Our research not only establishes a unified framework to describe the two SOIs, but also offers a new perspective for studying the SOIs in other physics.
摘要：
In high-power laser systems for inertial confinement fusion, hot images may be intense enough to damage expensive optical components. Basing on split-step fast-Fourier-transform algorithm, the intensity and location of hot images of a spectrally dispersed sinusoidal phase modulated laser beam is numerically investigated. It is found that, the time-average intensity of hot image firstly decreases monotonically with the modulation depth and eventually reaches a certain minimum, then increases slowly and reaches a saturated value; in addition, with the modulation frequency and the grating dispersion coefficient increasing, the time-average intensity of hot image decreases generally; while the location of hot image always does not change. Finally, the influence of the distance from the obscuration to the nonlinear optical element on the suppression effect of spectral dispersion of sinusoidal phase modulated light on formation of hot images is discussed. The result is helpful to appropriately choose parameters of the spectrally dispersed sinusoidal phase modulated light to minimize the threat of optical damage of hot image and improve the performance of high- power laser system.
摘要：
This study proposed a new hybrid approach for short-term water demand prediction. Raw water demand data were decomposed into a set of intrinsic mode functions (IMFs) component and a residue by using ensemble empirical mode decomposition (EEMD) method. IMF1 is the main random component of the raw water demand data, the continuous deep belief neural network (CDBNN) model is used to predict IMF1. Other IMFs and residue can be recombined employing autoregressive integrated moving average (ARIMA) model for forecasting, this method reduces forecasting steps without increasing the forecasting error. The final forecasting result was obtained by summing the forecasting results of the two models. A historical hourly water demand data from an urban waterworks of Zhuzhou, China were investigated by the hybrid method. Simulation results indicate that the proposed approach has higher forecasting accuracy than back propagation neural network (BPNN), support vector regression (SVR), EEMD and their combinations.
摘要：
Parabolic phase is commonly utilized for concave or convex metalens. Here, we report for the first time using such approach for determinant diffusion of scattering waves in wide incident angles by arranging parabolic-phased subarrays in arbitrary coding sequences. To engineer multi-spectrum polarization-dependent bifunctional scatterings, multi-mode anisotropic meta-atoms are utilized without polarization cross-talking. For verification, two proof-to-concept coding metasurfaces are designed, fabricated and measured at microwave regime. Numerical and experimental results show that the -10 dB backscatter radar cross-section (RCS) reduction is clearly observed in C, X and Ku band. Moreover, the diffusion behavior can be engineered dual-polarized and even bifunctional by integrating vortex scattering. Our findings, free of time-consuming optimizations, opened a rapid, easy but very efficient way for stealth applications under bistatic detection.
摘要：
In this work, we present a method for generating vector vortex beams with metasurfaces. A Jones calculation is employed to theoretically analyze the phase and polarization transformation from metasurfaces. The experimental results are shown to agree well with our theoretical calculation. Lastly, as a geometrical representation, the hybrid-order Poincaré sphere is proposed to describe the evolution of polarization state and phase of light wave propagating in metasurfaces. The hybrid-order Poincaré sphere can intuitively demonstrate the change of polarization state and. So it can also become an effective tool to provide help in designing metasurfaces.
摘要：
In high-power laser system such as Petawatt lasers, the laser beam can be intense enough to result in saturation of nonlinear refraction index of medium. Based on the standard linearization method of small-scale self-focusing and the split-step Fourier numerical calculation method, we present analytical and simulative investigations on the hot-image formation in cascaded saturable nonlinear medium slabs, to disclose the effect of nonlinearity saturation on the distribution and intensity of hot images. The analytical and simulative results are found in good agreement. It is shown that, saturable nonlinearity does not change the distribution of hot images, while may greatly affect the intensity of hot images, i.e., for a given saturation light intensity, with the intensity of the incident laser beam, the intensity of hot images firstly increases monotonously and eventually reaches a saturation; for the incident laser beam of a given intensity, with the saturation light intensity lowering, the intensity of hot images decreases rapidly, even resulting in a few hot images too weak to be visible.
关键词：
Geometric phase gradient;Spin Hall effect of light;Metamaterial
摘要：
The spin Hall effect (SHE) of light originates from the spin-orbit interaction, which can be explained in terms of two geometric phases: the Rytov-Vladimirskii-Berry phase and the Pancharatnam-Berry phase. Here we present a unified theoretical description of the SHE based on the two types of geometric phase gradients, and observe experimentally the SHE in structured dielectric metasurfaces induced by the PB phase. Unlike the weak real-space spin-Hall shift induced by the SRB phase occurring at interfacial reflection/refraction, the observed SHE occurs in momentum space is large enough to be measured directly.
摘要：
In high-power laser system such as Petawatt lasers, the laser beam can be intense enough to result in saturation of nonlinear refraction index of medium. We present an analytical and simulative investigation of hot image formation in an intense laser beam through a saturable nonlinear medium slab based on Fresnel-Kirchhoff diffraction integral and the standard split-step Fourier method. The analytical results are found in agreement with the simulative ones. It is shown that, hot images can still form in an intense laser beam through a saturable nonlinear medium slab, additionally, the saturable nonlinearity does not change the location of hot images, while may decrease the intensity of hot images, i.e., the intensity of hot images decreases with the saturation light intensity lowering, and can stop to increase with the intensity of the incident laser beam heightening due to saturation of nonlinearity. Moreover, variations of intensity of hot images with the obscuration type and the slab thickness are discussed.
关键词：
Spin Hall effect of light;vector beam;spin accumulation
摘要：
We report the demonstration of intrinsic spin Hall effect (SHE) of cylindrical vector beam. Employing a fan-shaped aperture to block part of the vector beam, the intrinsic vortex phases are no longer continuous in the azimuthal direction, and results in the spin accumulation at the opposite edges of the light beam. Due to the inherent nature of the phase and independency of light-matter interaction, the observed SHE is intrinsic. Modulating the topological charge of the vector beam, the spin-dependent splitting can be enhanced and the direction of spin accumulation is switchable.
作者机构：
[Zou, Changqing; Peng, Xiaojiang] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.;[Chen, Shifeng; Zou, Changqing; Lv, Hao] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen Key Lab CVPR, Shenzhen, Peoples R China.;[Zou, Changqing] Univ Chinese Acad Sci, Shenzhen Coll Adv Technol, Beijing, Peoples R China.;[Fu, Hongbo] City Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China.;[Liu, Jianzhuang] Chinese Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China.
摘要：
The properties of fractional Fourier transform of anomalous vortex beams are studied. A new type of analytical expression of fractional Fourier transform for anomolous vortex beams is obtained. The properties of anomolous vortex beams on different fractional Fourier transform planes with different parameters are illustrated. The results show that the anomolous vortex beams always has a doughnut profile, the distribution of intensity on different fractional Fourier transform planes highly depends on the fractional order and the beam parameters, such as the beam order and the topological charge.
期刊：
2014 4TH IEEE INTERNATIONAL CONFERENCE ON INFORMATION SCIENCE AND TECHNOLOGY (ICIST),2014年:595-598 ISSN：2164-4357
通讯作者：
Wen, Yafei
作者机构：
[Wen, Yafei; Zou, Changqing; Liu, Jianzhuang] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen, Peoples R China.;[Wen, Yafei] Univ Chinese Acad Sci, Beijing, Peoples R China.;[Zou, Changqing] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.;[Liu, Jianzhuang] Chinese Univ Hong Kong, Huawei Technol Co Ltd, Dept Informat Engn, Media Lab, Hong Kong, Hong Kong, Peoples R China.
会议名称：
4th IEEE International Conference on Information Science and Technology (ICIST)
会议时间：
APR 26-28, 2014
会议地点：
Shenzhen, PEOPLES R CHINA
会议主办单位：
[Wen, Yafei;Zou, Changqing;Liu, Jianzhuang] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen, Peoples R China.^[Wen, Yafei] Univ Chinese Acad Sci, Beijing, Peoples R China.^[Zou, Changqing] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.^[Liu, Jianzhuang] Chinese Univ Hong Kong, Huawei Technol Co Ltd, Dept Informat Engn, Media Lab, Hong Kong, Hong Kong, Peoples R China.
会议论文集名称：
International Conference on Information Science and Technology
关键词：
3D model retrieval;bag-of-features;local shape descriptors;pLSA
摘要：
Sketch-based 3D model retrieval has recently attracted a lot of interest in the content-based 3D model retrieval community.We propose a novel method to solve this problem by using a latent topic model
关键词：
Pancharatnam-Berry phase;Photonic spin Hall effect;metasurface
摘要：
Observation of photonic spin Hall effect (SHE) manifested by spin-dependent splitting of light in a dielectric-based birefringent metasurface is reported experimentally. By designing the metasurface with homogeneous phase retardation but space-variant optical axis directions, we govern the photonic SHE via space-variant Pancharatnam-Berry phase originated from the local polarization manipulation of the metasurface, essentially, the spin-orbit interaction between the light and the metasurface. Modulating the polarization distribution of the incident light and/or the structure geometry of the metasurface, the photonic SHE could be tunable. This type of metasurface offers an effective way to manipulate the spin-polarized photons and a route for spin-controlled nanophotonic applications.
摘要：
Nanosecond-level pulses of specific shape is usually generated by stacking chirped pulses for high-power inertial confinement fusion driver, in which nonlinear imaging of scatterers may damage precious optical elements. We present a numerical study of the characteristics of nonlinear imaging of scatterers in broadband laser stacked by chirped pulses to disclose the dependence of location and intensity of images on the parameters of the stacked pulse. It is shown that, for sub-nanosecond long sub-pulses with chirp or transform-limited sub-pulses, the time-mean intensity and location of images through normally dispersive and anomalously dispersive self-focusing medium slab are almost identical; While for picosecond-level short sub-pulses with chirp, the time-mean intensity of images for weak normal dispersion is slightly higher than that for weak anomalous dispersion through a thin nonlinear slab; the result is opposite to that for strong dispersion in a thick nonlinear slab; Furthermore, for given time delay between neighboring sub-pulses, the time-mean intensity of images varies periodically with chirp of the sub-pulse increasing; for a given pulse width of sub-pulse, the time-mean intensity of images decreases with the time delay between neighboring sub-pulses increasing; additionally, there is a little difference in the time-mean intensity of images of the laser stacked by different numbers of sub-pulses. Finally, the obtained results are also given physical explanations.
期刊：
Proceedings - International Conference on Pattern Recognition,2014年:4570-4575 ISSN：1051-4651
通讯作者：
Wen, Yafei
作者机构：
[Chen, Shifeng; Wen, Yafei; Zou, Changqing; Liu, Jianzhuang] Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen Key Lab Comp Vis & Pat Rec, Shenzhen, Peoples R China.;[Du, Shuze] Chinese Acad Sci, Chengdu Inst Comp Applicat, Chengdu, Peoples R China.;[Du, Shuze; Wen, Yafei; Zou, Changqing] Univ Chinese Acad Sci, Beijing, Peoples R China.;[Zou, Changqing] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang, Peoples R China.;[Chen, Shifeng; Wen, Yafei; Zou, Changqing; Liu, Jianzhuang] Chinese Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China.
通讯机构：
[Wen, Yafei] C;Chinese Acad Sci, Shenzhen Inst Adv Technol, Shenzhen Key Lab Comp Vis & Pat Rec, Shenzhen, Peoples R China.
会议名称：
22nd International Conference on Pattern Recognition (ICPR)
会议时间：
AUG 24-28, 2014
会议地点：
Swedish Soc Automated Image Anal, Stockholm, SWEDEN
会议主办单位：
Swedish Soc Automated Image Anal
会议论文集名称：
International Conference on Pattern Recognition
关键词：
3D model retrieval;bag-of-features;feature fusion;shape descriptor
摘要：
Sketch-based 3D model retrieval provides a convenient way for users to search for 3D models by sketches. Traditionally, this task is converted to a sketch-based 2D shape retrieval problem by projecting 3D models to 2D images. Local invariant features have been widely used to tackle this problem. However, it suffers from the lack of global context and easily fails when images of different 3D models share multiple similar regions. In this paper, we propose a joint description by fusing local statistical structures and global spatial features. Our description is invariant to scale, translate and rotation. An improved bag-of-features retrieval framework is applied to explore semantic visual word representations. Besides, a novel relevance feedback scheme which combines weight balancing and query modification is designed to further improve the retrieval performance. We conduct various experiments on the common sketch-based watertight model benchmark. The comparative results show that our approach significantly outperforms three state-of-the-art methods, demonstrating its effectiveness and robustness for sketch-based 3D model retrieval.
摘要：
Influence of space-time focusing on spatiotemporal instability in dispersive self-focusing media is investigated on the basis of a modified nonlinear Schrodinger equation (NLSE) beyond the slowly varying envelope approximation. It is found that, for both normal and anomalous dispersions, space-time focusing may lead to the appearance of new instability regions. Space-time focusing influences the original spectra obtained using the standard NLSE mainly by shrinking the instability regions, especially in the case of normal dispersion.
期刊：
Proceedings of SPIE - The International Society for Optical Engineering,1994年2070:525-527 ISSN：0277-786X
作者机构：
[SUN, CY] HENGYANG TEACHERS COLL,DEPT PHYS,HENGYANG 421008,PEOPLES R CHINA.
会议名称：
Fiber Optic and Laser Sensors XI
会议时间：
Boston, MA, United States
会议论文集名称：
Fiber Optic and Laser Sensors XI
摘要：
In this paper, the possible survey of a high-pressure field by using dual core fiber sensors and a differentiator electric bridge is described. Also, the interaction between high-pressure field and a dual core fiber nonlinear coupler is discussed, using the analyzed theory. We have obtained the formula of the theory and some correlative experimental results. We can measure high-pressure (2.2 * 10<sup>6</sup> V) by using dual core fiber sensors and a differentiator bridge.
